Thermionic emitter designed to control electron beam current profile in two dimensions

An x-ray tube, comprising:

• a vacuum enclosure;
• an anode positioned within the vacuum enclosure and including a target surface;
• and
• a cathode spaced apart from the target surface, the cathode including an electron emitter assembly comprising:
• a refractory metal foil configured for emitting a beam of electrons that is thermally controlled in two dimensions, the refractory metal foil comprising:
• first and second end portions disposed substantially in a first plane, a middle portion that is disposed substantially in a second plane that is offset from and parallel with the first plane, and a plurality of cut-outs that define a plurality of horizontal rungs.

An x-ray device, comprising:

• a vacuum enclosure;
• an anode positioned within the vacuum enclosure and including a target surface;
• and
• a cathode spaced apart from the target surface, the cathode including an electron emitter assembly comprising:
• a refractory metal foil emitter configured to emit a beam of electrons that is focused in two dimensions, the refractory metal foil comprising:
• first and second end portions, a depressed middle portion, and a plurality of cut-outs that define a plurality of rungs, with the plurality of rungs being interleaved with the plurality of cut-outs,
• wherein each rung has a middle portion and two end portions, the middle portion having a relatively wider cross-section than the end portions, and
• wherein the cross-section of each rung is selected to balance current density, resistance, and thermal conduction and radiation such that a focused beam of electrons is collectively emitted from the rungs.